Figure 6.

Human WNV disease cases in Iowa (2002–2005) compared to state mean NDVI scores. Total human WNV disease cases in Iowa by year (2002–2005) plotted against scaled mean NDVI scores from 2002–2005. The mean NDVI scores were calculated by calculating an average NDVI raster based on 14 separate scenes from March until September of each year. The mean NDVI score for each year was then calculated from this raster and plotted against the number of WNV disease cases.